Container forming method and apparatus



Oct. 30, 1962 'r. FLINT ETAL 3,061,158

v CONTAINER FORMING METHOD AND APPARATUS 5 Sheets-Sheet 1 Original FiledJan. 23, 1958 Oct. 3-0, 1962 T. FLINT ETAL CONTAINER FORMING METHOD ANDAPPARATUS 5 Sheets-Sheet 2 Original Filed Jan. 23, 1958 I Oct. 30, 1962T. FLlNT ETAL 3,061,158

CONTAINER FORMING METHOD AND APPARATUS Original Fi led Jan. 23, 1958 5Sheets-Sheet 3 I III IIIII I II uu uu u u an in MujLi I h u Oct. 30,1962 T. FLINT ETAL CONTAINER FORMING METHOD AND APPARATUS Original FiledJan. 23, 1958 5 Sheets-Sheet 4 COM Oct. 30, 1962 -r. FLINT ETALCONTAINER FORMING METHOD AND APPARATUS Original Filed Jan. 23, 1958 5Sheets-Sheet 5 hired lldtQS Patented Oct. 30, 1962 3,061,158 CONTAINERFORMING METHOD AND APPARATUS Thomas Flint, Concord, and Robert J.Robinson, Lexington, Mass, assignors to W. R. Grace & (10., tlambridge,Mass, a corporation or Connecticut Original application .lan. 23, 1958,Ser. No. 710,672, now Patent No. 2,986,076, dated May 30, 1961. Dividedand this application Feb. 9, 1961, Ser. No. 99,000

2 Claims. (Cl. 22632) The present invention relates to the manufactureof containers open at one end and sealed at the other from continuouslengths of flexible and stretchable tubing. The invention is moreparticularly concerned witha method and apparatus of this characterwherein the tubing contains blocks of printing at spaced intervalstherealong and wherein the seal is made by application of a clip to thetwisted end of the tubing, followed by severing from the tubing of alength including the sealing clip and a block of printing.

The present application is a divisional application filed as a result ofa requirement of restriction under Title 35 U.S.C. 121 in our copendingparent application Serial No. 710,672, filed January 23, 1958, PatentNo. 2,986,076.

The sealing of foodstuffs in impermeable, flexible and preferablytransparent containers from which the air has been exhausted has comeinto extensive use. Such containers are economically made fromcontinuous lengths of tubing, but the nature of the material, includingits stretchability, has been an obstacle to efiicient high speedmanufacture from the material in such form. A part at least of the labelfor the goods to be packaged in the container desirably is preprinted onthe tubing at spaced intervals; obtaining proper registry of such blocksof I printing on the completed containers presents a difficult problem.Where such containers have been made by hand-operated machines, the cutend of the tubing has not been satisfactory for the open end of thecontainer because of the irregular, jagged nature of the cut edge whichis too weak for the customers purposes. The operators applying the clipsrequire a length of several inches on both sides of the clip forhandling purposes and this introduces a waste of several inches oftubing for each container. Previous methods of manufacture produced manycontainers which had leaks through the clip-sealed end, resulting inhigh inspection costs and high reject rates. Hand operated machines areinherently slow in operation, leading to high labor cost.

An object of the invention is to provide an eflicient machine and methodfor making in a continuous operation a series of containers open at oneend and sealed at the other end from lengths of flexible and stretchabletubing.

Another object is to provide such a method and machine wherein blocks ofprinting on the tubing are properly registered on the finishedcontainers.

Another object is to provide such a machine and apparatus wherein theend of the tubing is prepared for sealing by application of the clip bybeing first regularly pleated and then twisted. v

A further object of the invention is to provide such a machine which issubstantially automatic in operation, provides proper registry of blocksof printing on the completed containers and provides clip-sealed endswhich are tightly sealed.

A further object is to provide such a machine and method wherein thecut, open end of the container is provided by a cut edge which is asmooth curve and which, therefore, has substantial strength.

Further objects are to provide such a method and apparatus wherein wasteallowance for sealing of the tubing is substantially eliminated andwherein the cost of inspection and the reject rate is very low.

Another object of the invention is to provide such a machine and methodwherein the seals are dependably and reliably formed.

A further object is to provide such a machine and method wherein thetubing is taken from a supply at a uniiorm rate and under uniformtension.

A further object is to provide a method and apparatus for feeding stripmaterial having a series of spaced markings thereon to a work stationstep-by-step with each marking accurately registered at the work stationduring a dwell of the material.

Other and further objects and features of the invention will be apparentfrom the following specification in which reference is made to theaccompanying drawings, wherein:

FIG. 1 is a perspective view partly broken away of a presently preferredembodiment of a machine of the invention whereon our method may bepracticed;

'FiG. 2 is a perspective view, similar to FIG. 1, but' with partsomitted, showing in more detail the tubing supply let-off mechanism;

FIG. 3 is a perspective detail view of the mechanism for pleating thetubing;

FIG. 4 is a vertical cross sectional view of the pleating mechanismtaken on line 44- of FIG. 3;

FIG. 5 is a similar vertical cross section through the pleatingmechanism, taken on line 55 of FIG. 3;

FIG. 6 is a diagrammatic perspective view of the tubing differentialwhereby the tubing is kept taut as it is taken from the let-oilmechanism of FIG. 2 at a uniform rate and is advanced step-by-step tothe work station by the tubing feed mechanism;

FIG. 7 is a perspective diagrammatic view of the tubing feed mechanism;

FIG. 8 is a diagrammatic perspective view of the mechanism for twistingthe tubing;

FIG. 9 is a detail view of a part of the mechanism of FIG. 8illustrating the operation of the twisting mechanism;

FIG. 10 is a View similar to FIG. 9, but showing a later stage of thetwisting operation;

FIG. 11 is a perspectiveview of the mechanism at the work station atwhich the tubing is twisted, sealed and cut off.

In accordance with the invention the flexible tubing from which thecontainers open at one end and sealed at the other are to be formed isfed step-by-step into a work station at which the sealed container iscompleted. The tubing is initially taken from a supply at asubstantially uniform rate and under uniform tension, pleated whiletraveling at said uniform rate and tension, and after pleatingmaintained taut and under the uniform tension in its advance from thepleating operation to the work station. At the work station a length ofthe pleated tubing is twisted, a sealing clip is applied over a part ofthe twisted portion, the remainder of the twisted portion is untwistedpreparatory to cutting and the tubing is then cut off close to theleading side of the clip. The feed mechanism at each step feeds up theproper length of tubing to provide a container of the desired length,with a block of printing, if present, properly registered thereon.

Referring to the drawings, in general organization the embodiment of themachine selected for purposes of illustration of the invention comprisesa main frame 2 on and under which the various mechanisms are carried. Atone end of the frame is a tubing supply, indicated generally at 4-, fromwhich the tubing is drawn by drawofi rolls at 6. From the draw-offrolls, the tubing passes station it passes through the tubingdifferential, indicated generally at 18, which maintains the belts andtubing taut and converts the step-by-step travel of the tubing at the.feed mechanism into uniform travel of the tubing at the pleater,without disturbing the uniform tension set up in the tubing at thetension control 8.

The tubing supply at 4 comprises a spindle 2d supported for rotation onthe upright 22 carried by the main frame 2. A long length of the tubing24 from which the containers are to be formed is carried on the spindle2 in the form of a roll 26 of flattened tubing. The tubing, asindicated, is fed from the roll 26 by being drawn therefrom by thedraw-off rolls at 6 and rotation of the roll 26 is opposed by a slightbraking action applied to the roll by a brake 28. The retarding effectof the brake is continuously adjusted under the control of a feeler 29which rides on the circumferential surface of the roll 26. As the roll26 decreases in diameter the feeler 29 moves closer to the axis of thespindle 20 and, through appropriate connections to the brake 28,decreases the retarding effect of the brake to compensate for thedecreased moment arm and thus provides that the tubing is drawn from theroll against substantially constant resistance.

The tubing between roll 26 and the draw-off roll assembly 6 is inflated,as appears in FIG. 2, with a bubble of air, which may serve tofacilitate inspection of the tubing by an operator if desired or topermit detection of pinholes or other flaws in the tubing.

The tubing 24 may be provided with spaced blocks of printing 3*), suchas may be desired to form a label or part thereof for the completedcontainer. F or the purpose of accurately registering each block ofprinting at the sealing station with the point at which the tubing willbe sealed, I may provide, as a part of the printing, black dots 32between the blocks of printing to serve as eye spots for aphoto-electric registering device which forms part of the feed mechanismhereinafter to be described in detail. The eye spots 32 are spaced aparta distance equal to the desired length of the containers. it will beappreciated that in some cases the printed label itself, or some portionthereof, may serve the same purpose as the eye spots.

The draw-off assembly 6 comprises a pair of rolls 33, 34. As the tubingis gripped in the nip of the rolls it is drawn from the roll 26 and atthe same time effectively deflated so that the air in the length betweenroll 26 and rolls 33, 34 is a trapped stationary bubble and need not bereplenished during the run of a roll of tubing. The rolls 33, 34 aredriven, FIG. 1, through suitable connections by a hydraulic motor 35.The tubing 24 is taken away from the draw-off rolls under constanttension by the tension control at 8 next to be described.

*From the draw-off rolls 33, 34 the traveling tubing 24 passesdownwardly about a stationary guide roller 36 and thence upwardly andabout a dancer roll 33. The dancer roll is carried for free rotation onarms 46 and 42, each pivoted, as at 44, on the machine frame 2. From thedancer roll the tubing passes downwardly, around guide roller 46adjacent the guide roller '36 and thence into the pleater 10.

The dancer roll 38 is biased to move in a direction away from the guiderollers 36, 46 by a tension spring 48 connected at one end to the arm 42below its pivot 44 and adjustably anchored at its other end to themachine frame 2. A similar spring, not shown, likewise acts on the arm40.

The hydraulic motor 35 which drives the draw-off rolls 33, 34 is driventhrough a variable-delivery hydraulic pump 50 through suitable piping52. The pump 53, in turn, is driven from the electric motor 54. The rateof delivery of hydraulic fluid from the hydraulic pump 5 is varied inaccordance with the position of the dancer roll 38 through a mechanicallinkage 56 leading from the lower end of arm 42 to the pump 56. Movementof the dancer roll 38, under the influence of spring 48, in thedirection away from guide rolls 36, 46 in response to any decrease belownormal in the tension in the tubing passing about the dancer rollresults, through linkage 56, in alteration of the delivery from pump 5to decrease the delivery of hydraulic fluid to motor 35, tending todecrease the speed of the draw-off rolls 33, 34 and thereby decrease therate of travel of tubing from these rolls to the dancer roll, thusincreasing the tension in the tubing passing about the dancer roll.

correspondingly, any increase above normal in the tension in the tubingat the dancer roll results in a proportionate increase in the speed ofthe draw-off rolls 33, 34, decreasing the tension at the dancer roll.Thus the tension in the tubing leaving the dancer roll is continuouslyregulated and maintained constant. Any change in tension, originatingeither in the tubing supplied to the dancer roll 33 from rolls 33, 34 orin the tubing drawn from the dancer roll and into the pleater, isautomatically corrected by change in speed of the draw-off rolls 33, 34and the tension in the tubing passing to the pleater restored to itsnormal value.

The normal value of the tension in the tubing 24 at the dancer roll 38can be adjusted to that desired by adjustment of the length of thetension spring 43 at its adjustable connection to the frame 2.

The tubing passes from the tension control 8 into the pleater at 16.Referring to FIGS. 3, 4 and 5, the pleater comprises a series of upperslats 6% depending from an upper plate 62 and a series of lower slats 64extending upwardlyintermediate the upper slats, from a lower plate 6, asis shown particularly in FIG. 4. Each slat extends generallylongitudinally of the pleater, in the direction of travel of the tubing24, and the slats are spaced apart transversely of this direction. Theupper slats increase in depth, the lower slats increase in height, andthe spacing between the slats decreases, all in the direction of tubingtravel. Near the entrance end 67 of the pleater the slats 69 do notsubstantially overlap the slats 64 in a vertical direction. The exit end68 of the pleater is narrower than its entrance end 67 and the slats atthis exit end are spaced more closely together and overlapped verticallyto a greater extent than they are at the entrance end 67, as appearsfrom a comparison of FIGS. 4 and 5. The tubing accordingly enters thepleater at 67 and is received between the slats substantially in flatform. The upper slats 64 form upwardly-opening folds in the tubing whilethe lower slats 64 form another, intermediate series ofdownwardly-opening folds, adjacent folds having one side in common. Dueto the decreasing spacing and the increasing vertical overlap betweenslats toward the discharge end of the pleater, the folds areprogressively deepened and brought together so that the traveling tubingemerges at 63 in pleated condition.

For practical reasons the eye spots 32 are printed on the tubinginwardly from the edge or fold of the flattened tubing. The spindle 20is tilted at an inclination to the axis of the draw-off rolls 33, 34 tocause the fold in the tubing to be repositioned so that the eye spots 32are located at the folded edge of the tubing as it enters the pleater10, appearing partly on one side of the fold and partly on the other.Thus, in the pleated goods every eye spot is visible whether theoutermost fold happens to be formed upwardly or formed downwardly in thepleater.

The tubing is taken from the pleater 1t) and carried to and through thework station by a pair of endless belts 69, 70 driven by the feedmechanism 14. Referring to FIG. 3, the return flight of belt 69 passesabout a guide roller 72 and the return flight of belt 70 passes about aguide roller 74. The guide rollers 72, 74 are positioned closelytogether so that the tubing leaving the pleater is firmly graspedbetween the belts and drawn from the pleater with the pleats completelyfolded together. Thereafter the tubing in the form of a flat pleatedstrip travels with the belts, being compressed and engaged between them,until the tubing passes into the work station. The belts then leave thetubing to by-pass the work station and re-engage the tubing leaving thework station, as a container, to eject it from the machine.

In their travel from the pleater to the feed mechanism the belts arecontrolled by the mechanism 18 shown in FIG. 6, which we designate thetubing differential, so that despite the step-by-step movements of thebelts and tubing at the feed mechanism, the tubing is taken from thepleater at a substantially uniform rate of speed and is maintained undersubstantially uniform tension during its advancing movement to the workstation.

Referring particularly to FIG. 6, the endless belts 69 and 70 with thepleated tubing between them lead from the guide rollers 72, 74 to andaround a freely rotatable tubing pulley 76, from the opposite side ofwhich they are led off to the feed mechanism 14. To maintain a uniformspeed of the belts at the guide rollers 72, 74 at which the tubing istaken away from the pleater, the tubing pulley 76 has imparted to it abodily reciprocating a motion in a direction endwise of the flights ofthe belts approaching and leaving the pulley,.and as shown by the arrow77 in FIG. 6. This reciprocating motion is timed with the step-by-stepfeed imparted to the belts at the feed mechanism 14 so that during adwell of the belts and tubing at the feed mechanism the pulley 76 istranslated to the left, as seen in FIG. 6, at the rate which Will takeup the belts from the guide rollers at average tubing speed, maintainingthe belts and tubing taut and under uniform tension. During a feedingmovement of the belts at the feed mechanism the pulley 76 is translatedto the right, as seen in FIG. 6, to give up the required amount of beltand tubing to the feed mechanism while at the same time continuing totake up belt and tubing leaving the pleater at the average tubing speed.

Both the feed mechanism and the tubing differential 18 are driven from amain shaft 78 which rotates continuously in the direction shown by thearrow and at the rate of one revolution for each container which isformed. The shaft 78 drives the feed mechanism intermittently through aroller gear 80 and drives the tubing differential continuously from abevel gear 82.

The bevel gear 82 meshes with a bevel gear 84 on shaft 86 which througha change gear 88 drives the pulley 94 through pinions 91 and 92 and thepulley shaft 90. An endless belt indicated generally at 96 passes aboutpulley 94 and leads about idler pulleys 98 and 100 which are supportedin fixed position for free rotation on the machine frame 2. The belt 96also passes, as shown, about a pulley 102 which is driven intermittentlyby the roller gear 80. The belt 96 also passes, in the manner shown inFIG. 6, about a pair of pulleys 104. 106 which are carried for freerotation on a yoke 108 so that they are bodily movable together. Theyoke 108 is supported on the frame 2 in a suitable guideway for movementalong a straight path parallel to the flights of belts 69, 70 leading toand from the tubing pulley 76. That is, the yoke 108, with the pulleys104, 106 linked by it, is confined to movement parallel to the directionof the arrow 77 in FIG. 6 which also is the direction of motion of thetubing pulley 76. The tubing pulley is supported on frame 2 in asuitable guideway for free movement confined to the direction of arrow77. The pulley 76 is moved back and forth along its guideway by anoperating rod 109 at its one end adjustably connected to the pulleyshaft, as by a set screw 110, and at its other end 6 mechanicallyconnected to the yoke 108. Thus the pulley 76 is moved with and by theyoke 108.

The roller gear intermittently rotates its follower 111 which is fixedon shaft 112. The follower through shaft 112 drives shaft 114 which, inturn, through a change gear 116 and pinion 117 drives the pulley 102 onshaft 118.

The drive for the tubing feed mechanism also is taken from shaft 118, abelt 120 driven by pulley 122 on the lower end of shaft 118 driving thefeed mechanism through a feed differential later to be described. Thusthe drive of the feed mechanism and of the pulley 102 from main shaft 78is intermittent or stepby-step, and the drive of pulley 94 is continuousand in timed relation thereto.

The operation of the tubing differential just described is as follows:

When the follower 111 of roller gear 80 is at a dwell, and the tubingfeed thus likewise at a dwell, the flight B of the belts 69, 70 leavingpulley 76 does not move. The flight A of the belts approaching pulley76, nevertheless, is moved, continuously to draw the tubing from thepleater 10 at a uniform rate, by translation of the pulley 76 to theleftward as seen in FIG. 6. This translation of pulley 76 to theleftward is brought about as follows: Continuous rotation of shaft 78rotates the pulley 94; pulley 102 cannot turn as the follower 111 islocked in the gear 80. Thus the flight 124 of the belt 96 continuouslytravels in the direction of the arrow 126. Flight 128 of belt 96,however, at this time is not moving inasmuch as pulley 102 isstationary. The two pulleys 104, 106 thus bodily move together, andcarry the yoke 108 with them, to the left as seen in FIG. 6, at a speedwhich is one-half the average speed of the tubing. The yoke 108 throughoperating rod 109 moves the tubing pulley 76 to the left as seen in FIG.6 at one-half average tubing speed. As this movement lengthens bothflights A and B, and since flight B is fixed, flight A is thus moved tothe left at twice the speed of translation of pulley 76, drawing thetubing 24 from the pleater 10 at average tubing speed.

When the follower 111 of the roller gear 80 is driven, the pulley 102,stationary in the dwell stage, rotates. The tubing feed also is driven,through belt 120, moving flight B toward the work station and feedingthe tubing from this flight into the work station. This feed movement ofthe tubing must be at a speed which is greater than the average tubingspeed, to make up for time lost during the dwell. Rotation of pulley 102accordingly causes flight 128 of belt 96 to move in the direction of thearrow 130 at a speed more rapid than the speed of the continuouslymoving flight 124. The greater speed of flight 128 causes the linkedpair of pulleys 104, 106 to be moved with their yoke 108 to the right,thus, through operating rod 109, translating the tubing pulley 76 to theright, as seen in FIG. 6, at a rate such as to cause the flight A tocontinue to be drawn from the pleater at average tubing speed. Theflight A passes around the tubing pulley 76, which rotates freely on itsaxis, to flight B which is moving toward the work station. Thus duringboth dwell and drive of the roller gear 80, and of the tubing feed, thetubing is drawn from the pleater at substantially uniform speed and thetubing as it advances from the pleater to the work station is maintainedtaut and kept under constant tension.

Just before entering the work station the tubing is released from theendless belts 69, 70. The belt 69 passes about a pulley 132 and returnsabout an arrangement of idler pulleys, not shown in detail, to the guideroller 72 at which it again engages the traveling tubing. The otherendless belt, 70, leaves the tubing at the same point as it passes abouta pulley 134 and is returned about a series of idler pulleys to thepulley 74 for re-engagement with the traveling tubing.

The return flights of belts 69, Nate passed about idler pulleys whichare moved bodily with the pulley 76 to keep the return flights taut.This movable idler pulley for belt 69 appears at 136 and thecorresponding pulley for belt 70 appears at 137 in FIG. 1. Some of theidler pulleys for each return flight may be spring-tensioned to movebodily in the direction to further aid in keeping the return flightstaut.

The pulley 132 is driven from the pulley 134 and together they drive theendless belts (and feed the tubing) by mechanism now to be described.From the pulley 122, which, as has been described, is drivenintermittently by the roller gear 80, the belt 120 drives a first input138 to a feed differential 140. The output 142 of differential 140drives the feed pulley 134 through a belt 144, pulley 146 and shaft 148of pulley 134.

The drive of pulley 134 which would be provided by the first input 138only, just described, is designed to feed the tubing a fixed, butadjustable, amount always less than the length of the container to bemade. To provide the necessary additional length of feed and preciselyregister the blocks of printing at the work station, a second input tothe differential 140 is provided. This second input to differential 140is operated, from a photoelectric means which scans the tubing duringthe preceding dwell, to add an increment of feed to the fixed feedprovided by the first differential input 138, in accordance with thefinding of the photo-electric means as to the length of additional feedrequired to eifect exact registration of a block of printing at the workstation.

Referring to FIG. 7, the photocell 150 (FIG. 2) is during a dwell movedfrom its rest position a fixed distance, say two inches, to the left asseen in FIG. 7, i.e., opposite to the direction of travel of the tubing.Ths movement of the photo cell is effected by a cam 152 on shaft 78,through follower 154, lever 156, pivoted cn frame 2 at 157, and links153, 160. When the photocell has moved the distance, say one inch,required to sense an eye spot, the photocell locks a brake, not shown,which prevents further movement of the crank 162 which is pivoted at 157about the same axis as lever 156. A lug 164 on crank 162 rests on lever156 whereby the crank rotates with the lever 156 until the crank islocked by the photocell. Motion of crank 162 results in end 166 of link168 moving downwardly in slot 170 in a cam follower arm 172 which ispivoted at 173, near its upper end, on frame 2. The initial position ofend 166 is at the pivot 173 of arm 172. The distance, or rad'us, of thefinal position of end 166 from the pivot of arm 172 is proportional tothe distance traveled by the photocell 150 before detecting an eye spot.After photocell travel is completed and just as the roller gear beginsto move the tubing, a cam 174 on shaft '78 moves the follower arm 172through a fixed angle, thus through link 168 moving a rack 176 adistance proportional to the distance traveled by the photocell beforedetection of an eyespot. The rack 176, through gear 178 and an overrunning clutch, not shown, operates the second input to the feeddifferential 140. Further rotation of cam 152 returns the photocell 150to its rest position.

This second input to feed differential 140 gives, in this instance, oneinch extra of feed to the tubing to feed the eyespot to the correctlocation. The rest position of the photocell serves as a datum position,fixed with respect to the work station, from which, during each dwell ofa block of printing at the work station, the distance to the nexteyespot is measured by movement of the photocell 150. It will beappreciated, therefore, that this second-input arrangement, includingthe photocell, will accommodate inequalities in eyespot spacing, normalyslight, on the printed tubing. Scanning the tubing while it isstationary is highly advantageous and provides precise registry of theblocks of printing on the container at the work station and providesaccurate control of the container length.

The machine may be employed with tubing having eye spots, or equivalentspaced indicia, in which case the photoelectric mechanism describedwillaccurately register the indicia on the completed containers and willprecisely control the length of the containers to agree with the eyespot spacing. Or, the machine may be employed with unprinted tubing orthe like, in which case a dark flag is located adjacent the tubingapproaching the station in position to be sensed by the photocell in itsmovement away from its rest position. The spacing of the flag from therest position of photocell 150 is adjusted to give the length of feed bythe second input to the differential 140 required, when added to thefeed provided by the first input 138, to give the length of containerdesired. The length of feed provided by the first input 138 may beadjusted by changing the change gears 116, 117.

It will be appreciated that when we refer herein to the advance of thetubing from the tension regulating control 8 to the feed mechanism 14 asbeing at a uniform speed and tension we do not mean uniform in themathematically exact sense, as there may be variations to accommodateany diiferences in eyespot spacing, but we mean that the advance iscontinuous and is uniform as contrasted with the distinctly step-by-stepmovement of the tubing at the feed mechanism.

The method of and mechanism for accurately registering the blocks ofprinting at the work station is of gen eral utility in the art offeeding material and may be employed with other materials than thetubing hereof, and for registering spaced markings of other kinds thanthe described eyespots or block of printing.

At the work station 16 the pleated tubing is tightly twisted before theclip seal is applied. For this purrose the tubing is tightly gripped attwo spaced points which may be about 1% inches apart, by two similar griping and twisting mechanisms indicated generally at 180, andsimultaneously rotated by them, one turning in one direction and theother in the opposite direction.

Referring to FIG. 8, which is an exploded view, in each gripping andtwisting mechanism, a rack 182 is uged downwardly against a fixed stop184 by a spring 185. The rack 182 meshes with a gear 186 free on a fixedshaft 188, and a gear 190 which carries two gripping jaws 192. A secondrack 194, free to move ver icafly, meshes with both gears on their sidesopposite the rack 182, and thus with rack 182 completely locates thejawed gear 190. Each jaw 192 is pivoted at one end on a stub shaft 196fixed on gear 190 and each has a slct 198 at its other end, FIGS. 9 and10. Each jaw is mo ed 0- ward the other to grip the tubing by beingrotated on its shaft 196 by a pin 200, two of which, one for ea'h jaw,project from the face of a gear 202, located opposite the gear 190 in asimilar set of gears and racks wherein gear 204 corresponds to gear 186and rack 206 to rack 182. Rack 208 is adapted to be pulled downwardly byan operator 210 to operate the mechanism. Downward motion of rack 2:08moves the pins 200 and with them the jaws from the positions shown inFIG. 9 to the positions shown in FIG. 10 in which the tubing 24 istightly gripped. The tightness of the grip is determined by the force ofthe spring 185, as yielding of this spring to permt upward rnovementofrack 182 permits the gear 190 and jaws 192 to rotate bodily with thepins 200, preventing further closing motion of the jaws. Such rotationtwists the tubing, as desired.

Therset of racks and gears indicated generally at 212 constitutes theother twisting mechanism 180, p sit'oned on the other side of theclip-applying device 214, which similarly rotates the tubing, but in theopposite direction, to create a tight twist in position to receive aclip.

The clip-applying device 214 may be a standard commercial device, suchas that shown in Patent No. 2,733,- 442, adapted to place and tighten aclip such, for example, as that shown in'Patent No. 2,700,805, andtherefore need not be described in detail. Clips 216 are supplied to theclip-applying device 214 from a hopper 218, FIG. 1, over a track 220.The clip-applying device 214 is operated, through rod 222, by anysuitable means, from the main shaft 78, in proper timed relation withthe feeding movements of the tubing, to apply a clip during adwell ofthe tubing.

Applying the clip to a portion of the tubing which has been regularlypleated and neatly and tightly twisted we have found results in apleasing symmetrical clip-sealed end; the regularity of the gathering ofthe tubing under the clip results in much greater uniformity of sealingaction and in much more reliable seals, with the consequence that thecost of inspection and the loss resulting from rejection of containersare greatly reduced.

When the clip has been applied, the twisting mechanisms are operated inthe direction opposite that described to untwist the tubing. The tubingis then immediately severed close to the clip on its leading side,without wastage of tubing, by a flying knife 224, FIG. 11, alsooperated, in proper timed relation, from shaft 78.

Untwisting the tubing before cutting it off results in a cut edge whichis a smooth curve and not subject to tearing as is a ragged edge such ashas been heretofore produced.

The severed length of tubing, sealed at one end and open at the other,is gripped between portions of the return tlights of the belts 69, 70and upon the next feeding movement is ejected from the machine as afresh length of tubing is fed into the work station for the formation ofthe next container.

We claim:

1. In an apparatus for feeding strip material having markings at spacedpositions therealong into a work station in a series of steps so thatthe material intermittently dwells with one of said markings in properregistry at said station, means for feeding said material, a feeddifferential having two inputs and having an output for intermittentlydriving said feeding means an amount which is proportional to the sum ofthe amounts said inputs are driven, means for driving one of saidinput-s intermittently a fixed amount, means for measuring during eachdwell the distance of the next marking from a datum position fixed withrespect to said work station, and means for driving said second input anamount proportional to said measured distance, to cause the next feedingmovement of said feeding means to feed the material the distancerequired to position said next marking at the work station as determinedby said measurement.

2. A machine for making from flexible tubing having blocks of printingat spaced positions therealong containers open at one end and sealed atthe other end and each having thereon one of said blocks of printing,comprising means for feeding tubing to a work station stepby-step sothat the tubing intermittently dwells at said station, a feeddifferential having two inputs and having an output for intermittentlydriving said feeding means an amount which is proportional to the sum ofthe amounts said inputs are driven, means for driving one of said inputsintermittently a fixed amount, a photoelectric cell adjacent the portionof said tubing approaching said work station, means for moving saidcell, during a dwell, from a datum position fixed with respect to saidwork station, along said tubing in a direction opposite its direction offeed to scan the tubing for the position of the next block of printingthereon, and means for driving said second input an amount proportionalto the distance traveled by said photocell before it senses a block ofprinting, to cause the next feeding movement of said feeding means tofeed the tubing the distance required to position said next block ofprinting at the work station.

References Cited in the file of this patent UNITED STATES PATENTS2,029,919 Fuller Feb. 4, 1936 2,033,857 Smith et al Mar. 10, 193 62,199,708 Maxfield May 7, 1940 2,821,388 Crane et a1 Jan. 28, 19582,880,539 Frenkel et al Apr. 7, 1959

